International Research Center for Computational Mechanics, State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Faculty of Vehicle Engineering and Mechanics, Dalian University of Technology, Dalian 116024, People's Republic of China.
Nanotechnology. 2019 Jul 5;30(27):275702. doi: 10.1088/1361-6528/ab0cce. Epub 2019 Mar 5.
The effects of segregation of impurity molybdenum (Mo) atoms on the tensile mechanical properties of nanocrystalline nickel (Ni) are investigated with molecular dynamics simulation. The results show that the segregation of Mo atoms induces an obvious increase in the elastic modulus and strength of nanocrystalline Ni, and the strengthening effect is more significant with smaller grain size. When the grain size decreases below a critical value, at which the softening occurs in non-segregated Ni-Mo alloy, no evident softening phenomenon is observed in Mo-segregated systems. Furthermore, based on a bicrystal configuration, it is found that Mo atoms segregating to the grain boundary reduce the energy and mobility of the grain boundary, increasing the grain boundary stability and thus accommodating the strengthening. The present findings will shed light on the fabrication of high strength nanocrystalline materials by controlling the segregation of atoms.
采用分子动力学模拟研究了杂质钼（Mo）原子的偏聚对纳米镍（Ni）拉伸力学性能的影响。结果表明，Mo 原子的偏聚导致纳米镍的弹性模量和强度明显提高，且细化晶粒尺寸强化效果更为显著。当晶粒尺寸减小至一个临界值以下时，在非偏聚 Ni-Mo 合金中发生软化，而在偏聚体系中则未观察到明显的软化现象。此外，基于双晶结构，发现偏聚到晶界的 Mo 原子降低了晶界的能量和迁移率，增加了晶界的稳定性，从而提高了强度。本研究结果将为通过控制原子偏聚来制备高强度纳米材料提供指导。
